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When it comes to mountain bike design, there’s a lot to digest. Modern bikes have so much going on, it’s easy to glaze over while being bombarded with numbers, standards, and why the latest super bike is better in every way.

We hear a lot about stiffness, and that’s exactly what Duytan is wondering about when he asks, “Why would I want stiffer parts up front on my 29er MTB, such as a Fox 34 or Rock Shox Pike over a Fox 32 120mm? I am told it increases confidence. What does that mean? Do flexy parts have an increased risk of OTB?

That’s a great question as increased front end stiffness is often touted as a benefit on modern trail bikes, but rarely explained in depth. For starters, we need to differentiate between chassis stiffness and suspension “stiffness”. Often, forks that are set up with a firm compression setting or high air pressure are referred to as “stiff”, but this is not the stiffness we’re going to talk about.

Instead, we’ll focus on chassis stiffness which is how the fork resists twisting, and flexing side to side, and front to back. In general, forks like the Pike and the Fox 34 have larger stanchions and therefore larger lower castings. Modern forks also run thru axles which is a much more solid connection between the hub and the fork. Some forks like the Rock Shox Pike are even moving to larger surface areas for the hub end caps (Torque Caps) as a way to add even more stiffness at the hub. A stiffer chassis will improve both steering precision and control under braking and big impacts.

As for steering, to think of it in an extreme way – imagine your front fork was made of rubber. Now imagine going down a rough trail and trying to control your front wheel which is connected to your handlebar by a rubber fork. Doesn’t sound very fun, does it? That’s essentially what is happening on a very small scale with a more flexy (less torsionally stiff) front fork. The steering won’t be quite as precise which could lead to a less confident ride. Will the average rider notice the difference between a 32mm Fox fork and a 34mm Fox fork with the same axle system? Maybe, maybe not, but they probably would notice the difference between an entry level fork and something like a Fox 34 or Pike.

Stiffness of the fork also can affect the control of the bike under hard braking. If the fork isn’t adequately stiff front to back, heavy braking can cause the fork legs to flex or worse – shimmy under braking. This kind of response unsettles the bike under braking which is not ideal for keeping things under control. A fork that is stiffer front to back may also be a small help if you go a bit too nose heavy while landing a jump by absorbing the landing rather than bending backwards, so it theoretically could help prevent going OTB in the right instance.

Side to side stiffness is important for handling as well which is also a factor of the hub and axle combination. A stiffer fork in this direction will improve control when really pushing hard into berms and corners. Again, modern forks are so good that it will take a high level of riding to get to the point where this is noticeable, let alone an issue.

As for the answer to your question, stiffer is better at the front – to a point. When pushing a bike to the ragged edge, increased stiffness at the fork will yield better control and handling, but there is a such thing as too much stiffness up front. Fortunately, that’s not really an issue with the current crop of trail and enduro suspension forks.

Will a stiffer fork increase your confidence? It may to a small degree, but unless your current fork is a cheap model with a 9mm quick release up front, it probably isn’t worth the upgrade just yet. If you’re really concerned about increasing your confidence and decreasing your OTB risk, you’d be far better off spending your money on a lesson or two than marginal gains in terms of a new fork.

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5 COMMENTS

    • I know super skilled riders can go back onto junk bikes and outride beginners, but if there are 2 beginners starting out, wouldn’t the one with more confidence have less to fear, on top of having far less frustration?

      • Coaching will benefit any rider, whether you’ve been riding for 20 minutes or 20 years. A beginner rider on an older bike that has been coached will likely ride with more control and confidence than a beginner rider on a modern bike with no training or coaching. Does the bike help? Yes. How much it helps is a whole other ball of wax.

  1. Depends where and how you ride, and how much you weigh.

    From my experience owning both a Fox 32 and 34:

    On a smoother trail/hitting bumps straight on they feel practically identical.

    On a chunky and steep trail, I can *absolutely* tell the difference in torsional stiffness between a Fox 32 and a Fox 34. The 32 rides fine but the 34 is so much more predictable and doesn’t feel like it “squirms sideways” as much as the 32 = easier to just go for it, instead of feeling like i have to fight to keep the bike on my chosen line.

    I’m 155lbs and not a super aggressive rider- huckers and big riders will probably benefit more.

    All that said, at the end of the day it’s still the pilot not the bike.

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